Inductive Communication System with Increased Noise Immunity Using Low-Complexity Transmitter

• US 20080205489A1
• Filed: 06/20/2006
• Published: 08/28/2008
• Est. Priority Date: 06/23/2005
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Pinter, Robert, Muehlsteff, Jens, Such, Olaf, Thijs, Jeroen Andrianus Johannes
• Granted Patent: US 8,155,168 B2
• Time in Patent Office: Days
• US Class Current: 375/142
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H04B 14/04 using pulse code modulation

Abstract

The invention related to a modulator for a communications system. The modulator comprises a spread spectrum coder, a pulse code modulator having a signal input port connectable to a signal output port of the spread spectrum coder. The modulator performs a robust and error free modulation and coding scheme by using a modified spread spectrum scheme combined with pulse code modulation. The communication system contains a low data rate, noise robust modulation and coding scheme using a very simple transmitter. This results in a very straightforward transmitter circuit, reducing size and costs of the transmitter.

Claims

1. A modulator for a communications system, comprising a spread spectrum coder, further comprising:

a pulse code modulator having a signal input port connectable to a signal output port of the spread spectrum coder.

2. The modulator according to claim 1, wherein the pulse code modulator is adapted to encode a spread spectrum coded signal, yielded by the spread spectrum coder, in a pulse-code modulated signal.

3. The modulator according to claim 2, wherein the pulse code modulator is adapted to encode an instantaneous value of the spread spectrum coded signal into a sequence that is part of the pulse-code modulated signal.

4. A transmitter comprising a modulator according to claim 1, further comprising a pseudo noise generator, connectable to the spread spectrum coder.

5. The transmitter according to claim 4, further comprising a resonant circuit and switching means adapted to alternatingly energize and de-energize the resonant circuit in response to a signal generated by the modulator.

6. The transmitter according to claim 5, wherein the resonant circuit has a resonance frequency in the long wave range.

7. The transmitter according to claim 4, further comprising a magnetic transducer.

8. A demodulator for a communications system, the demodulator corresponding to a transmitter within said communications system and comprising a correlator, wherein the correlator is adapted to perform a correlation of a received signal and a reference signal, wherein the reference signal is representative of the system response of the transmitter when excited by a particular pulse-code modulated sequence, the particular pulse-code modulated sequence being representative of a selected pulse-code modulated value.

9. The demodulator according to claim 8, further comprising a peak detector, an input port of which being connectable to an output port of the correlator.

10. The demodulator according to claim 9, further comprising a spread spectrum decoder, an input port of which being connectable to an output port of the peak detector.

11. A data transmission system comprising a sent-site spread spectrum encoder and a receive-site spread spectrum decoder, further comprising a sent-site pulse-code modulator and a receive-site pulse-code demodulator interposed between the spread spectrum encoder and the spread spectrum decoder.

12. The data transmission system according to claim 11, further comprising a sent-site transmitter circuit, the transmitter circuit comprising a resonant circuit and switching means adapted to alternatingly energize and de-energize the resonant circuit in response to a signal generated by the pulse-code modulator.

13. The data transmission system according to claim 11, wherein the pulse-code demodulator comprises a correlator and a peak detector.

14. The data transmission system according to claim 13, wherein the correlator takes as input a signal as it is transmitted on a transmission channel between a sender and a receiver of the data transmission system.

15. A method for transmitting data from a transmitter to a receiver comprising the steps of:

performing a spread spectrum encoding on a signal representative of said data yielding a spread spectrum coded signal; and

performing a pulse code modulation on the spread spectrum coded signal yielding a pulse-code modulated signal.

16. The method according to claim 15, further comprising the steps of:

receiving the pulse-code modulated signal;

performing a correlation of the pulse-code modulated signal and a reference signal to obtain a cross-correlation, wherein the reference signal is representative of the system response of the transmitter when excited by a pulse-code modulated sequence, the pulse-code modulated sequence being representative of a selected value out of possible values of the spread spectrum coded signal;

performing a peak detection on the cross-correlation.

17. The method according to claim 15, further comprising the steps of:

alternatingly energizing and de-energizing a resonant circuit in response to the pulse-code modulated signal yielding a transmission signal;

sending the transmission signal over a transmission channel.